This invention relates to the field of ostomy products, and in particular to a coupling for releasably attaching an ostomy pouch to a pad or wafer worn on the body. The term xe2x80x9costomyxe2x80x9d is intended to be interpreted broadly, and includes colostomy, urostomy and ileostomy.
The invention relates in particular to a type of ostomy coupling in which a deformable ring, for example, a split ring (or a ring which behaves substantially as a split ring) is used to fasten two coupling members together.
Such ostomy couplings are described for example in GB-A-2301533, GB-A-2299761 and EP-A-0737456.
The ostomy couplings described in these documents have proved to be extremely reliable, and yet easy to use. The resilient split ring can provide a secure mechanical fastening which is unlikely to come apart by accident; yet the fastening can be released when desired by simple manipulation of the split ring by finger, to enable the coupling members to be separated.
In addition, the couplings have excellent sealing characteristics, provided by a deflectable sealing wiper, which provides a large area axial seal over an annular band region. The seal performance is important because the human nose is extremely sensitive to the malodours within an ostomy pouch. If gases escape, for example, during physical movement while wearing the pouch, the odours can be extremely embarrassing for the wearer.
In general, seal performance may be affected by factors including manufacturing (moulding) tolerances; shrinkage of one or both of the coupling members during attachment to an adhesive wafer or to an ostomy pouch (after moulding); and bending or distortion of the coupling members while the ostomy pouch is being worn. For a deflectable seal, a relatively high sealing area is preferred to a so-called point seal, as this is able to accommodate wider variations to provide a reliable seal, in use.
Generally it is desirable for the coupling height to be a small as possible, so as to be comfortable and unobtrusive to wear. The minimum profile height of a split ring ostomy coupling is limited by a number of factors, including:
(a) The length of the deflectable seal, and the axial seal seat, required to provide a high sealing area (band), to achieve a reliable seal in use.
(b) The configuration of the coupling member profiles and the necessary material thicknesses, to support the split ring captively and movably on one of the coupling members, and to achieve a secure mechanical interlock between the coupling members.
Broadly speaking, a first aspect of the invention is to provide an ostomy coupling member comprising a curved seal surface acting as a seat for a deflectable seal of a complementary coupling member. By using a curved seal seat surface, a relatively large seal area can be provided in a small profile height.
In one form, an ostomy coupling member comprises a channel region, a first wall of the channel tapering in a curved taper towards the second wall such that the width of the channel narrows with a curved taper towards the channel floor.
Preferably, the channel is wider (at least at one point) than it is deep.
In one embodiment, the channel is substantially continuous (for example, annular or another closed loop shape). However, in an alternative embodiment, a segmented channel is used.
Preferably the channel, or at least the seal seat surface, is generally annular, although other closed loop shapes may be used as desired.
In another aspect, a coupling member comprises an annular seal having a curved configuration.
In another aspect, the invention provides an ostomy coupling comprising a first coupling member releasably securable to a second coupling member by means of a deformable coupling member behaving a split ring carried by one of the coupling members, the first coupling member comprising a seal seat surface which curves in a generally radial direction, and the second coupling member carrying a deflectable seal which, in use, bears against the curved seal seat when the coupling members are secured together.
In another aspect, the invention provides an ostomy coupling member having an annular channel extending radially inwardly from the side of the coupling member, the coupling member carrying a deformable ring or split ring received within the channel, wherein the ring or split ring is shaped to form a generally smooth (e.g. rounded or tapered) shape or contour transition with the coupling member.
Such a smooth contour is advantageous to avoid sharp edges of the coupling from being visible through the user""s clothing, and to avoid sharp edges from possible catching on the wearer""s clothes.
Preferably, the ring has a tapered or inclined outer surface. Preferably, the contour or profile of the coupling member with the ring mounted thereon is generally trapezoid.
Preferably, the ring comprises at least one projection (tab) for projecting through an aperture in the coupling member.
Preferably, the coupling member comprises a second channel, and the aperture or apertures communicate with the second channel.
Preferably, the ring is, or behaves substantially as, a split ring.
In another aspect, the invention provides a coupling member comprising at least one generally radially projecting guide, the coupling member carrying a deformable ring or split ring mounted on the guide, the ring (or split ring) having a channel means therein for receiving the guide, such that portions of the ring fit on either side of the guide to hold the ring captive on the guide.
Preferably, the ring is, or behaves substantially as, a split ring.
Preferably, each arm of the split ring is bifurcated to form the channel means.
The above aspects may be used independently. However, additional advantages can be achieved by using two or more of these aspects in combination. In particular, the preferred embodiments illustrate configurations of coupling members which can enable the height of a split ring coupling to be reduced without detracting from the excellent mechanical fastening and seal properties of the coupling.